Shadow Brexit secretary Keir Starmer will say in a speech in Birmingham that Labour will try to amend the government’s EU withdrawal bill.
Photograph: Andy Hall for the Observer

Labour will table amendments to the government’s EU withdrawal bill aimed at preventing the UK from crashing out of Europe without a deal if parliament rejects the outcome of the Brexit talks, Keir Starmer will say on Monday.

In a speech in Birmingham, the shadow Brexit secretary will pledge to work with colleagues from other parties to try to amend the government’s key piece of Brexit legislation in an attempt to strengthen parliament’s say.

The Brexit secretary, David Davis, has repeatedly promised to put the withdrawal agreement to a “meaningful vote” in both houses of parliament, but ministers have suggested the only option if the government loses will be to leave the EU without a deal in place.

Starmer will say: “The government’s own Brexit minister Lord Callanan said just last week that if the deal is voted down it would be ‘an instruction to move ahead without a deal’.

“That is totally unacceptable. If parliament rejects the prime minister’s deal, that cannot give licence to her – or the extreme Brexiteers in her party – to allow the UK to crash out without an agreement. That would be the worst of all possible worlds.

“That is why in the coming days – and working with others in the Lords and the Commons – Labour will ensure that an amendment is tabled to the EU withdrawal bill to strengthen the terms of parliament’s meaningful vote.”

Labour would like the bill to say that if the Brexit deal is rejected, MPs should pass a motion setting out the government’s next steps, which Starmer would like to include going back to the negotiating table in Brussels.

“This would provide a safety valve in the Brexit process to safeguard jobs and the economy. It would remove the possibility of a no vote leading to a no deal. It would bring back control to parliament,” he will say.

On Monday, Tony Blair will continue his crusade against Brexit, urging parliament not to allow the government to “fudge” the question of Britain’s future relationship with the EU until after March next year.

“As time goes on, it will become crystal clear that the government’s original negotiating position was built on sand. They will realise that they are in mortal danger of putting a proposition to parliament which will not pass … so the government will turn to fudge,” the former prime minister is expected to warn.

“It is this strategy that parliament has a duty to foil. It has demanded a meaningful vote. The vote is only meaningful if it is on a proposition which allows us to know with precision what our future path looks like before we take it.”

The EU withdrawal bill is currently making its way through the House of Lords, with the report stage – at which amendments are likely to be made – due after Easter.

The legislation then passes back to the Commons, and Labour hopes that if key amendments pass with strong majorities in the Lords, including support from crossbench and Tory peers, pro-remain Tory MPs could be encouraged to rebel against May.

Smith, who was sacked after setting out his views in a Guardian article, has said he will continue to speak out from the backbenches about the need for Labour to continue asking whether Brexit is the right thing for Britain, and to offer voters the chance to accept or reject the final deal at the ballot box.

The prime minister also persuaded fellow leaders to back her claim that there was “no other plausible explanation” for the Salisbury poison attack than Russian state involvement.

On Thursday May will make a whistle-stop round-Britain tour to mark a year until Brexit day in March 2019. Kicking off in Scotland, she will visit all of the home nations, meeting parents, workers, farmers and EU citizens to explain the government’s approach and hear their views.